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Docjohn
10-06-2008, 11:42
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I bought a used 300mw blue laser that was removed from a RGBLP1000 RGB projector (made in Hungary). The blue laser head and the driver board were removed from the projector and sold on e-bay. The owner wanted to increase his blue power with another blue. The driver board requires an input of 12v, 5v, and a 0-5v. analog input for modulation. They were connected by an umbilical cord. When all voltages were connected, It did not lase. :mad:

Observations

The 12v drew 1.5 A. and was labeled TEC. The 5v. drew 4.5 A. The mod input drew 1ma no matter where it was set (0 to 5v.)

The heat sink of the driver and the heat sink of the laser head got warm as expected.

Nothing was registered on a LPM in front of the laser (no IR)

No current changed anywhere by varying the mod input voltage.

The voltage reading on the board where the 5v. 4.5A connected read 3.2v at the board and did not change by changing the 5v input. (just like a zener diode)

Questions :confused:



Do the currents sound right?

Is the 3.2v 4.5A going to the laser head probably driving the IR diode(s)?

How could I determine if the IR diode(s) are good or DOA?




4017


Thanks for any advice :)




Docjohn :):):)

pelosh
10-06-2008, 12:10
Hi

I can not answer any of your questions, but I would like to know what sort of blue is it supposed to be and what make of laser was it (how old etc.).

Cheers

stanwax
10-06-2008, 12:35
That looks like (and should be based on the system model number) a blue laser by RGB in hungary. Its likely to be 473nm DPSS rather than 44xnm from diodes.

Dont concern yourself with the current draw from the mod input - its a control input that will show only negligable current draw - that said if it pulls an amp or 2 then you may have a prob ;)
What would be of greater use is to vary the mod input and observe the 5V power supply current consmuption. There will be a significant (maybe an amp) draw on this with zero volts on the mod input, as the diode will likely be biased so that it will be just below threshold at zero input. The current should increase in a reasonably linear fashion as you increase the mod input volts. The current of 4.5A may seem alot but there will be a multiwatt 808 pump diode in there so I doubt thats a crazy figure. I am concerned however that the volts are dropping to 3.2V - can your PSU supply enough current? - i would hope it can and am not trying to insult you - just important to know!

One thing you can do is use a ccd camera (webcam mobile phone) to look for ir. Place a white card a few inches from the output and look at the card through the camera. If you see a pink/purple glow then there is ir being emitted. If its really bright then the head may well be working but the SHG may not be functional. If you see no glow on the card try pointing the camera directly into the laser output window. This may seem daft but if there is enough ir coming out to damge the camera you would see the glow on the card. Doing this you may see some ir glow inside, if you do and its faint then the diode may well have gone to diode heaven.

As you rightly pointed out the head should get some warmth as the TECs do their job but if its getting very hot very quickly this could be a problem and explain why there is no blue output as Blue DPSS need pretty close control of temperature to work.

Hope it helps - keep us informed and keep asking questions.

Rob

PS look on the edge of the driver card - it says RGB LAser Systems :)

allthatwhichis
10-06-2008, 13:19
Welcome to the forum DocJon. The laser you bought was posted here by a member. Here is the thread... http://www.photonlexicon.com/forums/showthread.php?t=5351

You should PM Kyle and ask how he had it set up. That is not a run of the mill laser and I am not sure how much helo most of us will be compared to Kyle since he used to own that unit. I am sure someone here can help, but Kyle would be the best to ask.

stanwax
10-06-2008, 13:31
Well spotted - I did wonder if it may be THAT laser. I guess one thing is true then it will work and not be a rip off purchase as I beleive Kyle to be a reputable seller. Drop him a line Im sure he will point you in the right direction.

BTW Those RGB manufactured lasers are very nice quality....

Rob

Docjohn
10-06-2008, 14:56
Hi all:

I did get it from Kyle. He has been very helpful and fair. I am trying to see if I can get it working.

The 5v supply is rated at 40 amps. The 12 volt at 20 amps ,and the mod voltage at 1.5 A. I am using 3 separate bench power supplies,one for each voltage, so I know the voltage and current going to each point on the PCB of the driver.I wonder if using 3 separate supplies is a problem. I can't see how but who knows.

The thing that purplexs me the most is no change in the 5v current going to the IR diode by changing the mod vovtage. If the IR diode is in diode heaven, would you see that?

Thanks, John :):):)

stanwax
10-06-2008, 15:04
Ok so I guess them PSUs are up to the job!

As for the diode, yes you would see the current change - most of the time when a didoe fails they fail due to the optical cavity breaking down therefore the electrical characteristics remain largley unchanged. This is not the only failure mode but the most common, so I would expect if the diode is dead in the traditional mode, that you would still see the current changing as you modulate.
Im sure Kyle can and will get you going

Rob

MechEng3
10-06-2008, 15:16
Sounds like a dead diode to me....I have one here that was a 20 watter. It gave up after a 35 amp surge......my fault TEC not ready for that kind of cooling.. Now a dim red led......no change in current draw. No worries....I have more Hate to hear that though....hope I am wrong.

Docjohn
10-06-2008, 16:07
So a dead IR diode may or may not still pull varying current when modulated depending on the method of failure?

John :):):)

Docjohn
10-06-2008, 18:43
One thing you can do is use a ccd camera (webcam mobile phone) to look for ir. Place a white card a few inches from the output and look at the card through the camera. If you see a pink/purple glow then there is ir being emitted. If its really bright then the head may well be working but the SHG may not be functional. If you see no glow on the card try pointing the camera directly into the laser output window. This may seem daft but if there is enough ir coming out to damge the camera you would see the glow on the card. Doing this you may see some ir glow inside, if you do and its faint then the diode may well have gone to diode heaven.



I did as you instructed. When I point the camera into the output of the laser with all lights off I can see a very faint violet-blue dot. Shall I say a prayer for a deceased IR diode? :(

John :):):)